Globular cluster populations in Coma ultra di ff use galaxies - PowerPoint PPT Presentation

“Stellar halos across the cosmos” July 2-6, 2018, Heidelberg Globular cluster populations 
 in Coma ultra di ff use galaxies Sungsoon Lim 
 Peking University, China Collaborators: Eric W. Peng (Peking University, China) 
 Patrick Cote (National Research Council of Canada) Laura V. Sales (UC Riverside) Mark den Brok (AIP , Potsdam) (Lim et al. 2018 ApJ accepted 
 John P . Blakeslee (Gemini Observatory) 
 arXiv:1806.05425) Puragra Guhathakurta (UC Santa Cruz)

UDGs are everywhere • Forty seven UDGs in the Coma cluster 
 (van Dokkum et al. 2015) • Five UDGs in the Virgo cluster 
 (Mihos et al. 2015; Beasley et al. 2016; Mihos et al. 2017) • Several UDGs in the Fornax cluster 
 (Muñoz et al. 2015) (DF44 in the Coma; 
 (DF4 in M101; 
 van Dokkum et al. 2015,2016,2107) Merritt et al. 2016) • About 300 UDGs in the Coma cluster 
 (Koda et al. 2015; Yagi et al. 2016) • Many UDGs in other galaxy clusters 
 (e.g. van der Burg et al. 2016; 
 Janssens et al. 2017; Lee et al. 2017) (UDGs in the Virgo; Mihos et al. 2015) • UDGs in less dense environments 
 (Martínez-Delgado et al. 2016; 
 Roman & Trujillo 2016a)

Globular Clusters • A good tracer of stellar population • GC specific frequency (S N ): 
 Number of GCs per unit luminosity of host galaxy • Empirical relation between 
 total number of GCs and total mass (ACSVCS; Peng et al. 2008)

Globular Clusters • A good tracer of stellar population • GC specific frequency (S N ): 
 Number of GCs per unit luminosity of host galaxy • Empirical relation between 
 total number of GCs and total mass (Harris et al. 2013)

GCs in UDGs • Large GC population in DF17 (Peng & Lim 2016) • Large GC populations in 
 VLSB-B, VLSB-D,VCC 615 
 (Mihos et al. 2015, 2018; 
 Toloba, Lim et al 2018) 
 DF44, DFX1 
 (van Dokkum et al. 2017) (Peng & Lim 2016) • UDG may also follow the relation between 
 N GC & M total .

GCs in UDGs • Large GC population in DF17 (Peng & Lim 2016) • Large GC populations in 
 VLSB-B, VLSB-D,VCC 615 
 (Mihos et al. 2015, 2018; 
 Toloba, Lim et al 2018) 
 DF44, DFX1 
 (van Dokkum et al. 2017) • UDG may also follow the (Toloba, Lim et al. 2018) relation between 
 N GC & M total .


 
 
 
 
 More GC studies • GCs of ~15 UDGs in Coma cluster central region using Coma Treasury Survey 
 - van Dokkum et al. 
 (2017,+3 additional UDGs); 
 - Amorisco et al.(2018) 
 (van Dokkum et al. 2017) (Amorisco et al. 2018)


 
 
 
 
 More GC studies • GCs of ~15 UDGs in Coma cluster central region using Coma Treasury Survey 
 - van Dokkum et al. 
 (2017,+3 additional UDGs); 
 - Amorisco et al.(2018) 
 (van Dokkum et al. 2017) (van Dokkum et al. 2015)


 
 
 
 
 More GC studies • GCs of ~15 UDGs in Coma cluster central region using Coma Treasury Survey 
 - van Dokkum et al. 
 (2017,+3 additional UDGs); 
 - Amorisco et al.(2018) 
 (van Dokkum et al. 2017) (van Dokkum et al. 2015)


 
 
 
 
 More GC studies • GCs of ~15 UDGs in Coma cluster central region using Coma Treasury Survey 
 - van Dokkum et al. 
 (2017,+3 additional UDGs); 
 - Amorisco et al.(2018) 
 (van Dokkum et al. 2017) Most UDG GC studies cover small number of UDGs or small area of the galaxy cluster. To explore UDG formation, we need a systematic GC study of UDGs over a large area of the cluster (van Dokkum et al. 2015)

Targets & 
 Observation • 34 UDGs 
 (our HST program - 
 26 orbits of HST ACS/WFC PID:14658; PI: Eric Peng 
 + DF17, Peng & Lim 2016) • 14 UDGs 
 (in Coma Treasury survey 
 + DF42, DF44, DFX1; 
 van Dokkum et al. 2017) • classical dwarfs in Coma Treasury survey 
 (den Brok et al. 2014)

Targets & 
 Observation • 34 UDGs 
 (our HST program - 
 26 orbits of HST ACS/WFC PID:14658; PI: Eric Peng 
 + DF17, Peng & Lim 2016) • 14 UDGs 
 (in Coma Treasury survey 
 + DF42, DF44, DFX1; 
 van Dokkum et al. 2017) • classical dwarfs in Coma Treasury survey 
 (den Brok et al. 2014)

Targets & 
 Observation • 34 UDGs 
 (our HST program - 
 26 orbits of HST ACS/WFC PID:14658; PI: Eric Peng 
 + DF17, Peng & Lim 2016) • 14 UDGs 
 (in Coma Treasury survey 
 + DF42, DF44, DFX1; 
 van Dokkum et al. 2017) • classical dwarfs in Coma Treasury survey 
 (den Brok et al. 2014) (van Dokkum et al. 2015)

Targets & 
 Observation • 34 UDGs 
 (our HST program - 
 26 orbits of HST ACS/WFC PID:14658; PI: Eric Peng 
 + DF17, Peng & Lim 2016) • 14 UDGs 
 (in Coma Treasury survey 
 + DF42, DF44, DFX1; 
 van Dokkum et al. 2017) • classical dwarfs in Coma Treasury survey 
 (den Brok et al. 2014) (van Dokkum et al. 2015)

Targets & 
 Observation • 34 UDGs 
 (our HST program - 
 26 orbits of HST ACS/WFC PID:14658; PI: Eric Peng 
 + DF17, Peng & Lim 2016) • 14 UDGs 
 (in Coma Treasury survey 
 + DF42, DF44, DFX1; 
 van Dokkum et al. 2017) • classical dwarfs in Coma Treasury survey 
 (den Brok et al. 2014)

Targets & 
 Observation • 34 UDGs 
 (our HST program - 
 26 orbits of HST ACS/WFC PID:14658; PI: Eric Peng 
 + DF17, Peng & Lim 2016) • 14 UDGs 
 (in Coma Treasury survey 
 + DF42, DF44, DFX1; 
 van Dokkum et al. 2017) • classical dwarfs in Coma Treasury survey 
 (den Brok et al. 2014)

GC Specific Frequency (S N ) • S N of UDGs varies a lot. • UDGs have higher S N than those of normal dwarfs.

GC Specific Frequency (S N ) • S N of UDGs varies a lot. • UDGs have higher S N than those of normal dwarfs. S N 1 σ Mean S N of 
 classical dwarf galaxies 
 in Coma

GC Specific Frequency (S N ) • S N of UDGs varies a lot. • UDGs have higher S N than those of normal dwarfs. S N 1 σ Mean S N of 
 classical dwarf galaxies 
 in Coma

GC S N connection to the galaxy size • Mean S N value increases with galaxy size. • This trend is getting weaker at faint UDGs.

GC S N connection to Environments The mean S N to be higher at the cluster center and lower in the outskirts.

Rapid quenching of SF 
 in the dense environment • In Liu et al. (2016) 
 (Liu et al. 2016)

High density GC Gas Stars Rapid quenching GC Young galaxies in 
 Old galaxies today the Early Universe Low density Gradual quenching Same final Di ff erent initial stellar masses total (gas) masses

Origin of massive UDGs? • Mean total mass of high S N UDGs 
 ~ total mass of M33 • Mean stellar mass of high S N UDGs 
 ~ 5% stellar mass of M33 • Based on SFH of M33, 5% of current mass of M33 were formed about 7 Gyr ago (Barker et al. 2011). • Above results suggest that M33 size galaxies fell into the Coma clusters about 7 Gyr ago , and their star formation was quenched , and eventually became High S N UDGs • Some UDGs have mean stellar ages of 7-9 Gyr (Gu et al. 2018; Ferre- Mateu et al. 2018; Ruiz=Lara et al. 2018).

Origin of massive UDGs? • Mean total mass of high S N UDGs 
 ~ total mass of M33 • Mean stellar mass of high S N UDGs 
 ~ 5% stellar mass of M33 • Based on SFH of M33, 5% of current mass of M33 were formed about 7 Gyr ago (Barker et al. 2011). • Above results suggest that M33 size galaxies fell into the Coma clusters about 7 Gyr ago , and their star formation was quenched , and eventually became High S N UDGs • Some UDGs have mean stellar ages of 7-9 Gyr (Gu et al. 2018; Ferre- Mateu et al. 2018; Ruiz=Lara et al. 2018). ~M total of M33

Origin of massive UDGs? • Mean total mass of high S N UDGs 
 ~ total mass of M33 • Mean stellar mass of high S N UDGs 
 ~ 5% stellar mass of M33 • Based on SFH of M33, 5% of current mass of M33 were formed about 7 Gyr ago (Barker et al. 2011). • Above results suggest that M33 size galaxies fell into the Coma clusters about 7 Gyr ago , and their star formation was quenched , and eventually became High S N UDGs ~5%M star of M33 • Some UDGs have mean stellar ages of 7-9 Gyr (Gu et al. 2018; Ferre- Mateu et al. 2018; Ruiz=Lara et al. 2018). ~M total of M33

Origin of massive UDGs? • Mean total mass of high S N UDGs 
 SFH of M33 (Barker et al. 2011) ~ total mass of M33 • Mean stellar mass of high S N UDGs 
 ~ 5% stellar mass of M33 • Based on SFH of M33, 5% of current mass of M33 were formed about 7 Gyr ago (Barker et al. 2011). • Above results suggest that M33 size galaxies fell into the Coma clusters about 7 Gyr ago , and their star formation was quenched , and eventually became High S N UDGs ~5%M star of M33 • Some UDGs have mean stellar ages of 7-9 Gyr (Gu et al. 2018; Ferre- Mateu et al. 2018; Ruiz=Lara et al. 2018). ~M total of M33

Origin of less massive UDGs? • Their M/L ratio is similar to classical dwarf galaxies. • Following scenarios can explain dwarf origin UDGs: 
 - Large angular momentum (or spin) of dwarf galaxies 
 (Amorisco & Loeb 2016; Rong et al. 2017) ; 
 - DM and stellar expansion of normal dwarf galaxies by feedback driven gas outflow 
 (Di Cintio et al. 2017; Andrew’s talk) ; 
 - Tidal e ff ects by environments 
 (Collins et al. 2013; Carleton et al. 2018) • Low S N UDGs are more elongated than high S N UDGs.